I came across an interesting single-chip processor in the General Instruments Microelectronics 1977 Data Catalog. They call it a Sequential Boolean Analyzer (SBA) and list it as "preliminary information", I have no idea if it was ever manufactured.

What's interesting about this chip is that it's a 1-bit RPN machine with many 30 i/o pins, a 16-level stack and supplementary storage. They specifically don't tell you if this is a microcoded design or implemented in hardware, but it's an interesting read from a theoretical design standpoint. Here's the pdf

I've never heard of an SBA before, are there other such implementations in hardware (or software)?

thanks for pointing this guy out. The first thoughts that came to my mind were:

- DSA (Digital Signal Analysis) and

- fast 'D/A converter' interpolation

I vaguely remember the first '1-bit D/A converter' inscription in a CD-player (a Sony 5-disc CD-carroussel, perhaps?) I saw in the 80´s and I wondered, at that time, that a set of 1-bit D/A converter/analyzer chips might have been introduced. Never had those thoughts anymore until now.

Would the RPN-structure enhance performance? The block-diagrams suggest it can be used as part of a fast process controller, and I can only understand output directly connected to the input when internal compensation occurs, and in this case, the 1023-word programming would find purpose if fast enough.

Based on the 80´s 'technology shift' that began to endorse fixed, fast and easily programmable/customizable hardware, I'd bet in a mid-term, well-balanced HW/SW implementation. My memory only points to the HP28 as one of the first well-know implementing of RPN-like stack through SW.

If memory helps, it somehows reminds me about the Motorola MC 14450 1-bit CPU, a rare IC that puzzled me around 1980, when I was a CMOS specsheet avid addict. However, I hadn't used it nor know any real application of it.

The MC14450 was an interesting processor too, here's the datasheet. This was really manufactured and I'm sure used somewhere, I don't thank that the SBA had the same traction.

What really caught my eye on the SBA chip was that section of the datasheet on stack manipulation commands, essentially: Enter, Swap [typo on this], Dup, Drop you don't see that much outside of HP calculator manuals!

Quote:
My memory only points to the HP28 as one of the first well-know implementing of RPN-like stack through SW

I never really through about that. I was certainly amazed when the HP28C came out with it's radically different and very advanced functionality. At the time, I happened to giving a talk at the HP offices in NY (about artificial intelligence) and was given one of the first HP-28C's as compensation. It was great fun to play with and very quickly disappointing because it had just 2K of RAM.

This same GI MicroElectronics Data Catalog lists their PIC as preliminary information too, which makes for a nice dichotomy of extreme success and likely failure. Stack-oriented machines just didn't make it. HP's 3000 line of computers were HW stack machines until PA-RISC came out and then it emulated the "classic 3000" instructions in SW. This happened at roughly the same time as the 28C came out.